U.S. patent application number 13/811949 was filed with the patent office on 2013-05-16 for sensor arrangement comprising magnetic index encoder in a bearing seal.
This patent application is currently assigned to CONTINENTAL TEVES & CO. OHG. The applicant listed for this patent is Henrik Antoni. Invention is credited to Henrik Antoni.
Application Number | 20130118273 13/811949 |
Document ID | / |
Family ID | 44534328 |
Filed Date | 2013-05-16 |
United States Patent
Application |
20130118273 |
Kind Code |
A1 |
Antoni; Henrik |
May 16, 2013 |
SENSOR ARRANGEMENT COMPRISING MAGNETIC INDEX ENCODER IN A BEARING
SEAL
Abstract
The invention relates to a sensor arrangement including a torque
sensor for measuring the torque acting on a first shaft and
including a rotational angle index unit. The first shaft is
supported by at least one bearing, the seal of the bearing
including a magnetic index encoder that is detected by at least one
magnetic sensor element.
Inventors: |
Antoni; Henrik;
(Freigericht, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Antoni; Henrik |
Freigericht |
|
DE |
|
|
Assignee: |
CONTINENTAL TEVES & CO.
OHG
Frankfurt
DE
|
Family ID: |
44534328 |
Appl. No.: |
13/811949 |
Filed: |
July 22, 2011 |
PCT Filed: |
July 22, 2011 |
PCT NO: |
PCT/EP2011/062653 |
371 Date: |
January 24, 2013 |
Current U.S.
Class: |
73/862.08 |
Current CPC
Class: |
F16C 33/78 20130101;
G01D 5/145 20130101; F16J 15/326 20130101; G01L 3/104 20130101;
F16C 41/007 20130101; G01L 3/101 20130101 |
Class at
Publication: |
73/862.08 |
International
Class: |
G01L 3/10 20060101
G01L003/10 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 4, 2010 |
DE |
10 2010 038 907.2 |
Jun 29, 2011 |
DE |
10 2011 078 281.8 |
Claims
1.-14. (canceled)
15. A sensor arrangement, comprising a torque sensor for the
measurement of torque acting on a first shaft and comprising a
rotation angle index unit, wherein the first shaft is supported by
at least one bearing, and wherein a seal of said bearing comprises
a magnetic index encoder, which is detected by at least one
magnetic field sensor element.
16. The sensor arrangement as claimed in claim 15, wherein the
magnetic field sensor element is associated with the index encoder
so that the magnetic field sensor element detects whether a
rotation angle of the shaft is at a defined rotation angle or in a
defined rotation angle range.
17. The sensor arrangement as claimed in claim 15, wherein the
index encoder comprises magnetic particles, which are arranged
and/or embedded in an elastomer, wherein said elastomer is
especially of annular form and is arranged as the seal of the
bearing.
18. The sensor arrangement as claimed in claim 15, wherein the
magnetic field sensor element is in the form of a switching sensor
element.
19. The sensor arrangement as claimed in claim 18, wherein the
switching sensor element is a switching Hall element or a switching
magnetoresistive magnetic field sensor element.
20. The sensor arrangement as claimed in claim 15, wherein the
index encoder comprises at least one magnetization as an index
mark.
21. The sensor arrangement as claimed in claim 20, wherein the
magnetization of the at least one index mark has a magnetization
direction which is essentially orientated axially relative to the
shaft, and wherein said magnetization is formed essentially
homogeneously within the index mark.
22. The sensor arrangement as claimed in claim 21, wherein the
index encoder comprises exactly one index mark or a plurality of
index marks with such a magnetization.
23. The sensor arrangement as claimed in claim 20, wherein the
index encoder comprises a main index mark and two, or a number
corresponding to a multiple of two, smaller auxiliary index marks,
wherein the auxiliary index marks are formed and disposed
symmetrically to the right and left sides in relation to the main
index mark.
24. The sensor arrangement as claimed in claim 23, wherein the main
index mark has a different magnetic polarity and/or magnetization
direction compared to the two at least immediately adjacent right
and left side auxiliary index marks.
25. The sensor arrangement as claimed in claim 20, wherein the
index encoder comprises a single main index mark and a single
smaller auxiliary index mark, wherein the main index mark covers
more than half the circumference in relation to the ring of the
seal, and wherein the main index mark has a different magnetic
polarity and/or magnetization direction compared to the auxiliary
index mark.
26. The sensor arrangement as claimed in claim 25, wherein the main
index mark covers more than 80% of the circumference in relation to
the ring of the seal.
27. The sensor arrangement as claimed in claim 15, wherein the
torque sensor comprises a first and a second shaft segment of the
first shaft, which are both connected together by a torsion rod and
are formed and arranged so as to be rotatable relative to each
other, and wherein a magnetic torque encoder is arranged on the
first shaft segment and two stator elements associated with said
torque encoder, each with protruding fingers, are arranged on the
second shaft segment.
28. The sensor arrangement as claimed in claim 27, wherein the
stator elements each comprise a soft magnetic ring element, which
comprises trapezoidal fingers protruding axially in relation to the
first shaft, wherein the fingers of the two stator elements mesh
together contactlessly and wherein at least one torque-magnetic
field sensor element is commonly associated with the stator
elements, by which the relative rotation angle between the first
and the second shaft segments is directly or indirectly detected,
from which the torque acting on the first shaft is derived.
29. The sensor arrangement as claimed in claim 15, wherein the
torque sensor is absent a torsion rod, and the torque sensor
comprises at least one of the following torque sensor elements, i)
strain gages, ii) a piezoelectric and/or piezoresistive sensor
element, iii) a magnetostrictive sensor element, iv) a sensor
element based on the use of surface waves, and wherein said at
least one torque-sensor element is connected directly or indirectly
to the first shaft and/or is formed and arranged so that it can
detect a torque acting on the first shaft.
30. A sensor arrangement for use in a motor vehicle, said sensor
arrangement comprising: a torque sensor for the measurement of
torque acting on a first shaft and comprising a rotation angle
index unit, wherein the first shaft is supported by at least one
bearing, and wherein the seal of said bearing comprises a magnetic
index encoder, which is detected by at least one magnetic field
sensor element.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is the U.S. National Phase Application of
PCT/EP2011/062653, filed Jul. 22, 2011, which claims priority to
German Patent Applications Nos. 10 2010 038 907.2, filed Aug. 4,
2010 and 10 2011 078 281.8, filed Jun. 29, 2011, the contents of
such applications being incorporated by reference herein.
FIELD OF THE INVENTION
[0002] The invention relates to a sensor arrangement, comprising a
torque sensor for the measurement of the torque acting on a first
shaft and comprising a rotation angle index unit and to the use of
the sensor arrangement in motor vehicles.
BACKGROUND OF THE INVENTION
[0003] More and more electronically assisted steering systems are
used in modern motor vehicles. For controlling said steering
systems it is necessary to detect the driver's command. A torque
sensor is usually used for controlling the steering system. For
determining the steering angle it is possible to determine the
steering position using an intelligent commutation sensor of the
steering assistance motor and a simple index sensor.
[0004] Owing to the desire to minimize the installation space in
the axial direction, a solution with an additional fastening
element is disadvantageous.
SUMMARY OF THE INVENTION
[0005] An aspect of the invention is a sensor arrangement that
implements a rotation angle index unit relatively inexpensively and
in a space-saving manner.
[0006] This is achieved according to the invention with the sensor
arrangement comprising a torque sensor for the measurement of the
torque acting on a first shaft and comprising a rotation angle
index unit, wherein the first shaft is supported by at least one
bearing, and wherein the seal of said bearing comprises a magnetic
index encoder, which is detected by at least one magnetic field
sensor element.
[0007] The preferred integration of the magnetic index encoder in
the bearing seal is characterized by a relatively high degree of
robustness.
[0008] It is preferred that the magnetic field sensor element is
associated with the index encoder so that the magnetic field sensor
element detects or can detect whether the rotation angle of the
shaft is within a defined rotation angle or range of rotation
angles or that the sensor arrangement is designed so that it can
detect and/or identify the angular position of the shaft relative
to a defined rotation angle and/or a defined range of rotation
angles.
[0009] The index encoder preferably comprises magnetic particles,
which are arranged or embedded in an elastomer, wherein said
elastomer is in particular of annular form and is arranged as a
seal of the bearing.
[0010] It is preferred that the magnetic field sensor element is in
the form of a switching sensor element, in particular as a
switching Hall element or a switching magnetoresistive magnetic
field sensor element.
[0011] The index encoder preferably comprises at least one
magnetization or a plurality of magnetizations as index marks. Here
the magnetization of the at least one index mark has a
magnetization direction that is in particular essentially
orientated axially relative to the shaft, wherein said
magnetization is particularly preferably formed essentially
homogeneously within the index mark. Most particularly preferably,
the index encoder comprises exactly one index mark or a plurality
of index marks with such a magnetization.
[0012] It is preferred that the index encoder comprises a main
index mark and two, or a number corresponding to a multiple of two,
smaller auxiliary index marks, wherein the auxiliary index marks
are formed and arranged in particular symmetrically on the right
and left sides relative to the main index mark. The main index mark
advantageously has a different magnetic polarity and/or
magnetization direction compared to the two auxiliary index marks
that are at least directly adjacent on the left and right
sides.
[0013] It is advantageous that the index encoder comprises a single
main index mark and a single smaller auxiliary index mark, wherein
the main index mark encloses more than half the circumference, in
particular more than 80% of the circumference, in relation to the
ring of the seal, wherein the main index mark has a different
magnetic polarity and/or magnetization direction compared to the
auxiliary index mark.
[0014] It is preferred that one or each index mark identifies or
enables the detection of a defined rotation angle or range of
rotation angles of the magnetic index encoder or of the first
shaft.
[0015] It is advantageous that the magnetic field sensor element of
the rotation angle index unit, which measures a magnetic field
produced by the permanent magnetic particles in the sealing surface
of the upstream roller bearing, i.e. the magnetic coding of the
seal as a magnetic index encoder, is mounted in the housing of the
torque sensor or laterally on the torque sensor.
[0016] The torque sensor and the rotation angle index unit are
preferably integrated in a common assembly. This enables production
costs and installation costs to be reduced. The sensor elements
and/or electronic components of the torque sensor and the rotation
angle index unit are in particular arranged on a common circuit
board and/or on a common chip.
[0017] It is preferred that the index encoder is connected
directly. or indirectly to the first shaft and rotates with the
same and that the corresponding magnetic field sensor element of
the rotation angle index unit is arranged in a fixed location and
contactlessly relative to the first shaft.
[0018] It is preferred that the torque sensor comprises a first and
a second shaft segment of the first shaft, which are both connected
to each other by means of a torsion rod and are formed and arranged
so as to be rotatable relative to each other, wherein a magnetic
torque encoder is arranged on the first shaft segment and two
stator elements associated with said torque encoder, each with
protruding fingers, are arranged on the second shaft segment. In
particular, the stator elements each comprise a soft magnetic ring
element, which comprises particularly preferably essentially
trapezoidal fingers axially protruding relative to the first shaft,
wherein the fingers of the two stator elements mesh with each other
contactlessly and wherein at least one torque-magnetic field sensor
element is commonly associated with the stator elements, with which
the relative rotation angle between the first and the second shaft
segments is directly or indirectly detected, from which the torque
acting on the first shaft is derived. Such a torque sensor has
proved to be relatively precise and reliable. This design of
trapezoidal fingers has proved to be particularly suitable for
relatively precise guidance of the magnetic field.
[0019] Advantageously, the two shaft segments are each in the form
of sleeves fixed on the first shaft or on the torsion rod.
[0020] Alternatively, the torque sensor preferably comprises no
torsion rod or is designed so that the torque on an essentially
stiff shaft is detected, wherein the torque sensor comprises at
least one of the following torque sensor elements, [0021] strain
gages, [0022] piezoelectric and/or piezoresistive sensor element,
[0023] magnetostrictive sensor element, [0024] sensor element based
on the use of surface waves, wherein said at least one torque
sensor element is directly or indirectly connected to the first
shaft and/or is formed and arranged so that it can detect a torque
acting on the first shaft.
[0025] The detection of the magnetic index encoder by the magnetic
field sensor element of the rotation angle index unit or by the
index sensor element preferably enables the determination of
whether the respective relative rotation angle between the first
shaft and a positionally fixed reference point or the index sensor
element lies within a defined index region or a defined overlap
region at a defined time point.
[0026] The sensor arrangement preferably comprises a common
housing.
[0027] The invention relates, moreover, to the use of the sensor
arrangement in motor vehicles, in particular as a torque sensor
arrangement with rotation angle index detection, particularly
preferably in the steering of a motor vehicle.
[0028] Advantageously, the invention also relates to a steering
system with one of the sensor arrangements or sensor arrangement
variants claimed or proposed above, wherein the first shaft is
directly or indirectly mechanically coupled to a drive unit, in
particular an electric motor or a hydraulic servo unit, so that the
drive unit can cause a rotary movement of the first shaft, wherein
the sensor arrangement comprises an angle sensor which detects the
rotation angle of the drive shaft of the drive unit as a second
shaft, wherein the angle sensor and the drive unit in particular
are designed so that the angle sensor can detect the absolute
rotation angle of the second shaft within a rotation.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] Further preferred example embodiments result from the
dependent claims and the subsequent descriptions of example
embodiments using figures.
[0030] FIGS. 1 through 5 show schematic example sensor
arrangements.
DETAILED DESCRIPTION OF THE INVENTION
[0031] In FIG. 1 an input side steering shaft (steering wheel side)
1 and an output side steering shaft (steering gear side) 2 are
illustrated, which are connected to a torsion rod. Said steering
shaft 1, 2 forms the first shaft, on which the acting torque is to
be measured by the torque sensor 3. A torque sensor 3 is
illustrated at the interface of the shaft ends, on whose circuit
board 4 a magnetic field sensor element 5 of a rotation angle index
unit is additionally attached. Magnetic field sensor element 5 is
associated with a seal 7 containing permanent magnetic material
forming an index encoder, which is in the form of a seal 7 of a
roller bearing 6 that supports the first shaft 1, 2.
[0032] In FIG. 2 the same construction is shown as is shown
schematically in FIG. 1, wherein the magnetization of an index mark
8 is formed in the axial direction relative to the shaft 1, 2. A
magnetized pole of the magnetized region 8 of the index encoder 7,
i.e. the index mark 8, is identified by "N".
[0033] The magnetized seal 7 is illustrated in FIG. 3 as an index
encoder comprising index mark 8. The magnetized region or index
mark 8 causes a magnetic field in the axial direction, which is
shown on the right in the diagram. The switching point SP of the
magnetic field sensor element of the rotation angle index unit is
significantly higher than an external magnetic field to be expected
of a parasitic magnetic field, which could cause erroneous
switching. The variation of the flux density Bz measured over the
angular position shows that the angular position of the switching
point SP is amplitude dependent. Said amplitude dependency
expresses itself in a changed switching point depending on the
distance between the magnet surface and the sensor element.
[0034] In order to improve the switching position, for example, as
illustrated in FIG. 4 as an index encoder example embodiment,
auxiliary index marks 9.1 and 9.2 with poles magnetized or formed
oppositely to the main index mark are disposed before and after or
to the left and right of the main index mark 10. The amplitude
dependency Bz, SP is thus significantly smaller.
[0035] Alternatively, the magnetization can also be formed over the
entire area of the magnetized sealing element, as in the example
embodiment of an index encoder illustrated in FIG. 5. The magnetic
field sensor element is thus permanently penetrated by a defined
magnetic field, whose direction changes at the switching point SP.
In this embodiment, significantly smaller magnetic fields can be
used because the switching point no longer has to deviate from the
null magnetic field to such an extent. For this purpose, the index
encoder comprises a main index mark 10, which includes more than
80% of the circumference of the encoder, and an auxiliary index
mark 9.
* * * * *